The first time I heard about neuro-linguistic programming, I was intrigued. By scrutinising and changing a person’s speech and body language, NLP promises to improve social and professional interactions.

It has, we’re told, the power to “unlock your capabilities”. Negative psychological patterns are identified, and can be “reprogrammed”. Sensitivity to others’ behaviour is also heightened. Indeed, by showing me how to “read” unconscious behavioural signs, it could allegedly help me be a better doctor.

The technique has been around since the 1970s. Its methods have been described enthusiastically in publications as respectable as the British Medical Journal, while the Royal College of General Practitioners is running NLP “master classes”. The course blurb says: “Neuro-linguistic Programming is the study of human excellence, in terms of how we can learn to take control of our consciousness … We know that an optimistic outlook and good emotional management improve health so it is important to teach others (and ourselves) how to change limiting beliefs and attitudes to restore health and maintain happiness.”